Optical flow refers to an image processing technique originally developed for computer and robot vision applications. In this Letter, optical flow algorithms are utilized to obtain two‐dimensional velocity fields corresponding to fluid flows. The performance of the algorithms with regard to three flows is discussed: computer‐simulated suspension flow, bubble detachment from a submerged needle, andinvivoblood flow in a microvascular network. For small changes in successive images, the algorithms yield good quantitative and qualitative information about the flows. ©1995 American Institute of Physics.